1. Field of the Invention
The present invention relates energy management in a sensor network environment. More particularly, the present invention relates to a method and a system for managing energy in a sensor network environment using a spanning tree, wherein the maximum number of allowable links is controlled to maintain the amount of energy consumed by sensor nodes distributed in the sensor network substantial uniform.
2. Description of the Related Art
As is generally known in the art, a sensor network is used to grasp the characteristics in a region (e.g. temperature), accurately locate an event, conduct remote monitoring, etc. Particularly, a number of sensors are distributed in a region and information is collected from the sensors and analyzed to extract desired data.
Such a process for distributing sensors in a sensor network requires that, when the sensors are using a limited power source (e.g. batteries), the sensors be distributed based on their energy efficiency. Although energy efficiency can be made substantially uniform by distributing specific sensors uniformly (i.e. at the same distance) over a region, it is substantially impossible to maintain the same distance between the sensors. When information collected by a number of sensors needs to be transmitted to an information collection device, such as a BS (Base Station), it is efficient to transmit information to a specific sensor from remaining sensors when energy efficiency is considered.
However, conventional sensor networks have a problem in that their sensor nodes do not consume energy uniformly. More particularly, the sensor nodes are installed at arbitrary locations and are connected in various network configurations. This is reflected in the routing path(s) for connecting the sensor nodes. As a result, when the sensor nodes transmit measurement data to the root of the spanning tree (i.e. BS), they consume different amounts of reception energy due to the varying number of their child nodes. In addition, the sensor nodes consume different amounts of transmission energy due to the different distance to their parent nodes. Furthermore, some sensor nodes may consume more energy in order to play their own role; some sensor nodes may have a faulty battery and begin their task at a much lower energy level than other sensor nodes; and, due to different environments in which the sensor nodes are located, some sensor nodes may consume energy more quickly than other sensor nodes.
As mentioned above, sensor nodes in the sensor network consume different amounts of energy as time elapses, and thus, the sensor nodes come to have different amounts of remaining energy. As a result, some sensor nodes have a shorter life than other sensor nodes. Such perishing of sensor nodes further shortens the life of remaining sensor nodes, as a new links are constituted to provide connection in the sensor network. Therefore, it is necessary to provide a method for maintaining the amount of energy consumed by the sensor nodes to be substantially uniform.